How can I speed-up my Webots simulation?

Question

My simulation is running correctly but is slow. How can I speed it up?

(I am part of the development team of Webots and we often get this question so I hope it will help some people!)

Answer 1

There are several ways to increase the simulation speed:

1. Use the Run button. This button runs the simulation as fast as possible using all the available CPU power. Otherwise, using the Real-Time running mode, Webots may not use all the available CPU power in order to slow down the simulation to match the real time.
2. Increase the value of WorldInfo.basicTimeStep. This field sets the granularity of the physics simulation. With a higher WorldInfo.basicTimeStep, the simulation becomes faster but less accurate. With a lower WorldInfo.basicTimeStep, the simulation becomes slower but more accurate. There is an additional restriction: WorldInfo.basicTimeStep must be chosen such as to be an integer divisor of the control step which is the value passed as a parameter to the wb_robot_step (or equivalent) function.
3. Decrease the value of WorldInfo.FPS. This field represents the maximum rate at which the 3D display of the main windows is refreshed. With a lower value, the simulation becomes faster but more flickering. With a higher value, the simulation becomes slower but less flickering.
4. Try changing the value of WorldInfo.optimalThreadCount. This field specifies how many threads are used to simulate the physics of the world. Depending on the world you can get a better performance by reducing or increasing this value. In general it is better to have a low number of threads for simple worlds and a bigger number of threads for complex worlds that include several robots physically independent from each other.
5. Disable unnecessary shadows. Webots uses a lot of CPU/GPU power to compute how and where the objects shadows are cast. But shadows are irrelevant for most simulation unless they should explicitly be seen by cameras. Unnecessary shadows can be disabled by unchecking the castShadows field of light nodes: PointLight, SpotLight, or DirectionalLight.
6. Simplify your simulation by removing unnecessary objects. In particular, try to minimize the number of Physics nodes. Avoid using Solid nodes when a Transform or a Shape node can be used instead.
7. Simplify the bounding objects to increase the speed of the collision detection. Replace complex primitives, like IndexedFaceSet, Mesh, ElevationGrid or Cylinder by simpler primitives, like Sphere, Capsule, Box and Plane. Avoid using a composition of primitives (in a Group or a Transform) when a single primitive would do the trick.
8. Set controller field to <none> for any Robot node that doesn't need to be controlled, instead of using the <generic> controller.